Earlier quoted context omitted.
Tilapia certainly does not refer to any whitefish. If tilapia is not "a fish" then neither are salmon or tuna or probably a dozen other common names.
Tilapia certainly does refer to (almost) any whitefish. Over 100 different fish are called 'tilapia'. Because their flesh is white, and they cannot pass as a more valuable fish. For comparison, there are 8 species of salmon. We eat maybe two of them.
All of which are cichlids.
That's a long way away from "any whitefish".
"Whitefish" most commonly refers to cod and pollock, not tilapia.
And we eat every species of salmon, not just two.